Evidence for the existence of substance P autoreceptor in the membrane of rat dorsal root ganglion neurons.
Substance P, a putative peptide neurotransmitter contained in primary sensory neurons, is suggested to play a major role in nociceptive transmission. In the present study, the existence of substance P autoreceptor in dorsal root ganglion neurons was identified with a method we developed recently and substance P-activated inward current in the dorsal root ganglion neurons and its ionic mechanism were also explored preliminarily. The majority of the cells examined (68/76, 89.5%) were sensitive to external application of substance P (0.01-10 microM) with a concentration-dependent inward current. This current was found to result from the opening of nonselective ion channel, preferring the Na+ channel. The substance P-activated current can be suppressed by Cd2+ (0.05 microM), which suggested Ca2+ may also be involved. Soon after the neurons had been identified to be endowed with substance P receptor with whole-cell patch-clamp technique, 17 cells were chosen for immunocytochemical staining to detect substance P-immunoreactivity. Seven neurons which were classified into small and intermediate size were found to reveal substance P-immunoreactivity. Using this method we have identified the existence of substance P autoreceptor in rat DRG neurons.
Hu
H Z
HZ
Research Center of Experimental Medicine, Tongji Medical University, Wuhan, People's Republic of China.
Li
Z W
ZW
Si
J Q
JQ
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002469:Cell Separation; D004594:Electrophysiology; D005260:Female; D005727:Ganglia, Spinal / Q000166:cytology* / Q000378:metabolism*; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D009474:Neurons / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D018040:Receptors, Neurokinin-1 / Q000378:metabolism*
D018040:Receptors, Neurokinin-1